There is known a hydraulic drilling machine comprising a drill tool and a hydraulic percussive mechanism. The hydraulic percussive mechanism includes a housing, a piston hammer, a pressure stabilizer, a liquid flow distributor, and a feeding air line with a source of compressed air. The pressure stabilizer serves to reduce inertia losses of the machine and increase the impact power of the hydraulic hammer, and has the form of a cylinder with a freely floating piston dividing the cylinder into a gas cavity and a hydraulic cavity. Part of the liquid that worked in the hydraulic hammer is conveyed to the hydraulic cavity. The gas cavity of the stabilizer communicates with the air network and with the idle stroke chamber (cf., SU, A, 337, 485).
However, in this hydraulic drilling machine the pressure stabilizer is structurally complicated, requiring a high degree of manufacturing accuracy of its moving parts.
One disadvantage of the above machine resides in that the moving parts are susceptible to fast wear, making the machine less reliable in operation.
From the working chamber of the hydraulic hammer the spent liquid is directed in a pulsed flow to the discharge line to be forced out of the discharge cavity of the hydraulic hammer by a plunger, which necessitates extra power consumption.
Another disadvantage is that operation of the pressure stabilizer requires the use of one more type of power in the form of compressed air.
There is also known a hydraulic drilling machine in which the hydraulic hammer accommodates in its housing a movable piston hammer, as well as work and idle stroke chambers periodically communicating with pressure and discharge lines by way of a hydraulic distributor, such as a rotary valve. The pressure line includes a hydraulic accumulator. The hydraulic hammer has one more hydraulic accumulator serving to reduce inertia losses of liquid in the course of the return stroke of the piston hammer. The hydraulic accumulator has the form of a cylinder whose interior is divided by a piston into two chambers of smaller and larger cross section. The first such chamber communicates continuously with the pressure line, whereas the second chamber communicates with the discharge line and periodically communicates with the pressure line in the course of the return stroke of the piston hammer (cf., SU, A, 354, 123).
However, in this hydraulic drilling machine the accumulator is overcomplicated, necessitating high manufacturing accuracy of the piston and precise centering of its elements.
In addition, the provision of a part movable on two surfaces speeds up wearing of the mating parts to result in a leak of the liquid through the piston and less reliable operation. The spent liquid is conveyed from the hydraulic percussive mechanism to the discharge line periodically by the piston and plunger to necessitate extra power expenditures.
The spent liquid moves along the discharge line in a pulsed flow to make the line less reliable.